1. Field of the Invention
The present invention relates to a device for treating patients suffering from a pneumothorax, tension pneumothorax, and/or hemothorax. The device is particularly unique in that it is does not require the assembly of parts and can be used by medical personnel with minimal experience and training in treating these conditions, and without additional supplies or instrumentation.
2. Description of the Related Art
Normally, the pressure in the lungs is greater than the pressure in the pleural space surrounding the lungs. However, collection of air the pleural space causes a loss of the negative pressure that causes the lung to collapse partially or completely. This condition is known generally as a pneumothorax. There are various types of pneumothorax including spontaneous pneumothorax, traumatic pneumothorax, and tension pneumothorax (synonymous with pressure pneumothorax or valve pneumothorax). Spontaneous pneumothorax exists in two forms, namely, simple spontaneous pneumothorax and complicated spontaneous pneumothorax. Simple spontaneous pneumothorax typically occurs suddenly or for no known reason. It is caused by rupture of a small air sac or fluid-filled sac in the lung, and most frequently strikes tall, thin men between the ages of 20 to 40. People with lung disorders, such as emphysema, cystic fibrosis, and tuberculosis, are at higher risk for spontaneous pneumothorax. Complicated spontaneous pneumothorax, also generally caused by rupture of a small sac in the lung, occurs in people with pre-existing lung diseases. The symptoms of complicated spontaneous pneumothorax, however, tend to be worse than those of simple spontaneous pneumothorax, due to the underlying lung disease. Spontaneous pneumothorax is characterized by dull, sharp, or stabbing chest pain that begins suddenly and becomes worse with deep breathing or coughing. Other symptoms include dyspnea, tachypnea, and cough.
Traumatic pneumothorax occurs as the result of accident or injury, either iatrogenic due to medical procedures performed to the chest cavity, such as thoracentesis or mechanical ventilation, or following chest trauma and resultant disruption of pleural integrity. Mechanical ventilation as it is used to treat adults and neonates with respiratory distress, is often performed at pressures greater than one atmosphere. Occasionally, barotrauma from this increased pressure results in lung disruption. Following chest trauma or lung barotrauma, air may enter the chest cavity via the damaged lung parenchyma, or through a defect in the chest wall, causing the lung to collapse.
When the abnormal accumulation of air in the pleural space is at a pressure greater than the ambient pressure, the pneumothorax is termed a tension pneumothorax. A tension pneumothorax is often the immediate result of an injury, the delayed complication of a hidden injury, such as a fractured rib, that punctures the lung; or the result of lung damage from asthma, chronic bronchitis, or emphysema. A physiologic one-way valve (secondary to damage in the lung parenchyma) allows air to enter the chest cavity, and become trapped. As inspiration becomes more difficult, the patient inspires with more force, or coughs thereby increasing his intrathoracic pressure, and air continues to be forced into the tension pneumothorax. As the pressure further increases, the mediastinal structures shift toward the contralateral chest, thereby decreasing venous return to the heart, and decreasing the ability of the heart muscle to fill during diastole. Due to this displacement, neither lung is able to properly inflate, and this cardiovascular and cardiorespiratory embarrassment is rapidly fatal if the tension pneumothorax is not promptly vented. The patient appears distressed, dyspneic, cyanotic, tachypneic and tachycardic. Distended neck veins, and a tracheal shift to the contralateral side are also key clinical signs. Early diagnosis is critical for patient survival. In-hospital patients who are being ventilated with positive pressure mechanical ventilation are often sufferers of occult tension pneumothorax, which develops exceedingly rapidly due to the high pressures used to mechanically ventilate them. Early diagnosis in this group of patients and prompt treatment is also critical for survival.
Hemothorax is the collection of blood in the thoracic cavity. It occurs when chest trauma is significant enough to damage any of the vascular structures in the thorax. As the thoracic cavity fills with blood, the lung has a decreased ability to expand normally, thereby decreasing oxygenation and ventilation. If a hemothorax continues to worsen, death may occur by exsanguination or hypoxia. Patients with large hemothorax may demonstrate signs of shock, and decreased neck vein distention. In patients with a combination of tension pneumothorax and hemothorax, death may occur due to any of the mentioned physiologic changes. In-hospital treatment of a hemothorax is similar to that of a pneumothorax and is accomplished by use of closed thoracostomy via a water-seal chest tube drainage device. Additionally, surgical intervention may be necessary to control the cause of the bleeding.
There are various known devices for treating these conditions. For example, U.S. Pat. No. 3,613,684 to Sheridan discloses a trocar catheter designed for the emergency treatment of a pneumothorax. A particularly disadvantageous feature of this device however, is that prior to using the device, a surgeon or other medical personnel must make an incision in the skin of the patient using a separate scalpel or knife. Further, the device provides an open communication between the chest cavity and the outside atmosphere. This device also requires a closed underwater seal system or other auxiliary equipment for proper operation. Given the urgency required in the treatment of a tension pneumothorax, the time required to retrieve and sterilize the scalpel and to make the incision prior to the insertion of this device and to connect the catheter to an auxiliary system could very well prove to be fatal. Moreover, because the medical personnel treating the patient is required to carry additional instrumentation in order to employ the device, the device is not well suited for pre-hospital use, use on battlefields, or other areas of mass casualty where storage and access to additional, sterilized medical instruments is extremely limited.
U.S. Pat. No. 4,153,058 to Nehme discloses a pleural decompression catheter for releasing entrapped air within a human body. The device consists of an elongated member axially insertable into a human body and having a fluid passage means for establishing fluid communication from the exterior of the elongated member to one end of the member positioned exteriorly of the body. A one-way valve is coupled to the exteriorly extending end of the elongated member. The one-way valve consists of a balloon which is attached to a relatively large exterior housing. Once the catheter is inserted into the patient, the trocar is removed in release the entrapped air within the chest cavity. The size and complexity of this device, however, renders this device ill-suited for use in emergency situations. Moreover, this device provides no means for affixing the device to the patient to ensure that the catheter is not prematurely removed from the patient when the patient is transported, or otherwise. In addition, as there is no means for securing the device to the patient, one is required to hold the exterior housing against the patient's chest so that the catheter does not shift or become disengaged. Additionally, the rigid nature of the external housing makes the device cumbersome if used in a pre-hospital setting, as warming blankets of the patient's garments would tend to dislodge the device. This precludes medical personnel from further tending to the patient and treating others.
U.S. Pat. No. 5,478,333 to Asherman, Jr. discloses a medical dressing for treatment of open chest injuries. The dressing consists of a discoid shaped dressing made of pliable plastic, having a central valve that extends away from the body when the device is employed. The disk has a skin adhesive on the side that is placed to the chest. The device is designed for pre-hospital use, however it is incapable of treating a tension pneumothorax in the absence of an open chest wound, as the device has no means to penetrate the chest and allow the tension pneumothorax to vent. Additionally, if used in conjunction with an intravenous catheter there is a threefold disadvantage in that (a) the catheter when inserted would cause a pneumothorax if one did not already exist, (b) the intravenous catheter when it is placed in the chest becomes a portal for contaminating the pleural cavity (especially in a chemical, biological, or radiologic battlefield environment), and (c) it would require assembly of parts and use of valuable time.
U.S. Pat. No. 5,344,410 to Kolkin et al., discloses a tubular rubber device for the drainage of pleural fluid. The device consists of a valve and plural fluid collection unit temporarily affixed to a stylet or mandrin that is inserted into the chest cavity. When the mandrin is removed, the rubber valve and collection assembly is removed. The device is not well suited for the pre-hospital treatment of tension pneumothorax because it is relatively large, and by its insertion through the chest wall causes a correspondingly large amount of tissue damage. Additionally, there is no easy way to affix the device to the skin of a patient once it has been employed. Further, the device requires that a scalpel be used to make the skin incision prior to its use, requiring medical personnel to carry additional instrumentation if they wish to use the device.
There is a need for a device that can be safely used by less experienced medical personnel, including first responders, to quickly and easily treat patients suffering from pneumothorax, tension pneumothorax, and/or hemothorax on battlefields, conditions of mass casualty, conditions of environmental chemical, biologic, or radiologic contamination, as well as in more conventional settings, such as within ambulances and hospitals.